This invention relates to dispensers for liquids and viscous semi-liquid products in general and more particularly to an improved liquid dispenser which utilizes a non-vented pump and does not need to be pressurized.
In my U.S. Pat. No. 3,211,346 there is shown a liquid dispensing apparatus which uses a non-venting pump to dispense liquid from a container. Because each time liquid is pumped out of the container a vacuum would otherwise be created therein, a compressed gas such as nitrogen is added to the container to maintain the product under pressure so that it may all be supplied to the pump and used. Although this dispenser works admirably well, it has a number of limitations. In particular, it is unable to dispense viscous products such as creams, foods (e.g., catsup, mustard, syrups) and liquid vitamins. Even where only a liquid is being dispensed my prior dispenser envisioned the use of metal containers or other heavy rigid containers which are not reusable, which is ecologically bad since they will not naturally recycle for many years. A type of arrangement which permits dispensing viscous products using a similar type of pump is that disclosed in U.S. Pat. No. 3,420,413 to D. F. Corsette. In the dispenser disclosed therein a pump withdraws a liquid or paste product from an air-tight container disposed within a rigid casing and collapsible under atmospheric pressure incident to withdrawal of the contents. It is clear that the air-tight collapsible container disclosed therein is relatively thick as is evidenced by the fact that the mouth of this container is of sufficient thickness to support the pump casing. The disclosed collapsible container, thus, has sufficient structural integrity that it is self-supporting when filled with the product to be dispensed, the use of the other container being primarily to provide a support for the pump to act against while pumping. Corsette discloses in another patent, U.S. Pat. No. 3,288,334 another arrangement of this type in which the collapsible container is constructed so as to be self-supporting even against the action of the pump. Other devices using a collapsible container and a pump are also known, for example the arrangement shown in U.S. Pat. No. 1,585,321 to Wilson. Wilson teaches a dispenser in which the collapsible container is in the nature of a tooth-paste tube or the like. In each of these cases the collapsible tube is essentially self-supporting and can be filled with the material to be dispensed prior to connection to the pump without the need for any additional supporting structure. Although this offers advantages with regard to pre-filling of these collapsible containers it degrades the efficiency of dispensing, since a container which must be structurally strong enough to provide the necessary support can not collapse as easily as might be desired and as a result a loss of material due to material being left in the container after full collapse can occur. Furthermore, in each of these containers the outlet of the collapsible container must be capable of supporting a pump attachment means such as a screw cap. This means that a special molding of the collapsible container is necessary along with a more complex molding of the pump arrangement itself so that it can be properly attached to the container. The problems in obtaining a good, air-tight connection are discussed in the Corsette U.S. Pat. No. 3,420,413 which deals primarily with means for obtaining an air tight connection at the closure between the pump and the collapsible container.
Thin collapsible plastic bags have been previously used, for example, in nursers for babies. Typical of such a collapsible bag is that disclosed in U.S. Pat. No. 3.204,855. A bag of this type insures almost complete collapse so that all the material contained therein will be dispensed. However, bags of this nature have not previously been considered for use in combination with a non-vented pump. Furthermore in these prior art dispensers very little attention has been paid to the use of materials which will naturally recycle when thrown out.
Thus, there is a need for a dispenser capable of dispensing both liquid and viscous products which can operate using a non-venting pump (which is less expensive and easier to manufacture than a venting pump), can be made at a low cost using inexpensive materials, the bulk of which will naturally recycle when thrown out. Furthermore such a dispenser should be capable of dispensing essentially all of the material contained therein and should offer ease of processing, i.e., ease filling and assembly.